The present invention relates generally to propelled bicycles and, more particularly, to a propelled bicycle with an automatic transmission. Preferably, the automatic transmission of the electric bicycle is dependent upon voltage generated.
Traditional pedal bicycles powered by the user via pedals are well known and are continuously improved upon. One such improvement includes the multi-speed bicycle, which has a plurality of gears. The user of the multi-speed bicycle may shift between different gears based on the users' preferred pedaling speed or based upon the terrain. Multi-speed bicycles have manual transmissions that allow the user to choose when to shift between gears. Generally, the user may shift a lever causing a cable to either pull or release depending on whether the user is up shifting or downshifting between gears. The cable may be used for various gearing systems such as a derailleur gears or an internally geared hub. When the cable is either pulled or released, it may facilitate a rear derailleur to derail the bicycle chain from one gear or sprocket to another gear or sprocket. The disadvantage of manual transmissions is that many bicyclists do not understand the logic of shifting gear levers to reach a desired balance between torque and speed. Unlike driving an automatic transmission automobile, gear shifting on a bicycle is not a simple linear progression, but a function of the ratio of the gear sizes, which may be variable. Many users may fiddle with the gear shifting levers. Shifting gears manually may not be accurate, it is possible to over- or under-shift due to an imprecise rear derailleur. Over- or under-shifting may cause the bicycle chain to slip off the gear or sprocket. To overcome these problems an automatic transmission for the multi-speed bicycle was invented.
The automatic transmission for a multi-speed bicycle is well known in the art. The automatic transmission may consist of a computer-controlled system within a gear shifter that monitors the speed and momentum of the bike usually via a wheel-mounted sensor. The computer system may process information to determine an appropriate speed at which to shift gears. The processor may instruct the gear shifter to pull or release the cable of the gearing system to shift between gears.
A further improvement upon the traditional pedal bicycle was the electric bicycle. The electric bicycle is well known in the art. The electric bicycle generally consists of a battery powered dc electric motor coupled to the bicycle frame. The electric bicycle may be powered by the electric motor. The user may choose not to pedal and rely on the electric motor to power the bicycle. Other advantages may include improved top speed, more power for traversing steep hills, more power for traversing a substantial amount of wind resistance or rough terrain when pedaling the bicycle may prove to be too difficult. Despite the various advantages, there may be a few disadvantages and inefficiencies associated with electric bicycles. Multi-speed electric bicycles with manual transmissions may be harder to determine when to shift gears because it may be harder for the user to judge or determine the appropriate gear when the rider is not pedaling.
The addition of an electric motor and a sufficiently sized storage battery to power the electric motor may add a substantial amount of weight to the bicycle frame. Electric bicycles may include the battery and the electric motor positioned near the upper portion of the bicycle frame. If the electric motor or battery is above the front hub or rear hub of the bicycle frame the center of gravity may be elevated. An elevated center of gravity may make turning the electric bicycle more difficult. The user of the electric bicycle may lose control or balance of the electric bicycle in situations where it is unlikely that a traditional pedal bicycle would encounter the same problem. Additionally, because the battery and electric motor may be bulky it may be uncomfortable for the user to ride the bicycle. The user may have to use caution to avoid contacting the battery or motor with his or her legs while riding.
Starting from rest with an electric bicycle may be very challenging. If a user would like to start from rest on a steep hill or difficult terrain, a substantial amount of torque may be required. Direct current electric motors generally have the highest torque output at high revolution per minute (“rpm”) range. Because the electric bicycles may only achieve the requisite torque at a substantial rpm level, the electric bicycle may not have enough power to start from rest.
Thus, there exists a need in the art for an improved electric bicycle.